1. Field of the Invention
The present invention relates generally to Digital Rights Management (DRM) in a portable terminal, and in particular, to an apparatus and method for controlling a rights object according to a change in a time zone in a portable terminal.
2. Description of the Related Art
DRM is technology used to protect content providers' rights and profits by preventing content from being illegally copied and distributed. Unlike analog content, digital content can be copied without loss. Thus, the digital content can be easily copied and distributed without permission. The DRM serves to protect the content providers against such infringement.
The content includes a media object and a rights object. The rights object has use authority for the content. For example, the rights object sets the use authority for the content such as playing, displaying, executing, printing, exporting or reading the digital works. The rights object, which has information about whether or not the use authority for the content exists, needs to be used to perform the DRM for the content used in a portable terminal.
The rights object uses reference values such as a use count, a use time and a use interval to set the use authority for the content. Here, the use count is used to set the number of available accesses to the content. The use time is used to set the absolute time from the time that the content is downloaded until the time that the content cannot be used. The use interval is used to set a predetermined time period from the time that the content is initially accessed. As a result, the rights object controls the use authority for the contents. If the rights object is completely consumed, the use authority for the content is terminated, so the content becomes unusable.
As described above, the rights object uses the reference values to set the use authority for the content. The use count among the reference values controls the use authority according to the number of times the content is used in the portable terminal, or the number of accesses to the content regardless of time zone. The use time and the use interval control the use authority according to the time zone in the portable terminal. For example, the use time and the use interval are managed only by the specified time in the portable terminal.
If the portable terminal moves across time zones, the absolute time in the portable terminal changes. The rights object using the use time or the use interval does not recognize the absolute time change in the portable terminal, and so the rights object manages the use authority according to the previously established time in the portable terminal. Thus, problems such as the abuse or unauthorized use of the content may arise. For example, when a user purchases content on Jan. 1, 2006, the content includes the rights object which uses a use interval as the use authority, the user can use the content for seven days as the use interval, and, thereafter, if the user moves into a different time zone which is, for example, 14 hours earlier than a previous time zone, there is the problem that the user will be prevented from using the content for 14 hours in the use interval. Similarly, when a user purchases content on Jan. 1, 2006, if the content includes the rights object which uses a use time as the use authority, the user can use the content until Jan. 2, 2006, and, thereafter, if the user moves into a different time zone which is, for example, 14 hours later than a previous time zone, there is the problem that the users will exceed their authorized use of the content beyond 14 hours.